Heat-Related Mortality in California Working-Age Adults From 2014 to 2023

Extreme heat events are increasing. Workers, especially those who perform physical activity or work outdoors, are at greater risk of heat-related death than the general population. California has the largest workforce of any US state and a high proportion of workers at risk of heat-related death. This study aimed to characterize heat-related mortality among California workers by demographics and industry/occupation to inform prevention.

Heat-related deaths among California residents likely to be in the workforce were analyzed from 2014 to 2023 using data from the Electronic Death Registration System. Cases included were those with a final or contributing cause of death coded as ICD-10 codes X30 (exposure to excessive natural heat) or T67 (effects of heat and light). Denominators for rate calculations were derived from the American Community Survey 5-year estimates.

There were 334 heat-related fatalities among working-age California decedents from 2014 to 2023. Most decedents were male (81%) and non-Hispanic White (42%) or Hispanic or Latino (42%). The overall mortality rate was 0.16 deaths per 100,000 workers per year. Among race/ethnicity groups, the heat-related mortality rate was highest in the non-Hispanic Black population (0.31). Individuals whose longest-held occupation was in the Agriculture, Forestry, Fishing, Hunting, and Mining industry group had the highest rate (0.60), followed by Construction (0.53). Those working in primarily outdoors occupations had a mortality rate 5 times higher than those working primarily indoors. Riverside County had the highest number of deaths (n = 104).

Tailored heat prevention strategies should be prioritized in high-risk industries, occupations, and regions to prevent fatalities among California workers.